PHYSICS LAZER LIGHT SECURITY SYSTEM 12TH GRADE PROJECT, Study Guides, Projects, Research of Physics

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PHYSICS PROJECT

Author: ABEL THOMAS

Grade: XII-A

Academic Year: 2019- 2020

School: INDIAN CENTRAL SCHOOL

PROJECT INDEX

1. BONAFIDE CERTIFICATE

2. ACKNOWLEDGEMENT

3. DECLARATION

4. INTRODUCTION

5. THEORY

6. COMPONENTS

7. CIRCUIT DIAGRAM

8. EXPERIMENTAL SET UP

9. WORKING

10. OBSERVATIONS

11. ADVANTAGES

12. CONCLUSION

13. PRECAUTION

14. BIBLIOGRAPHY

ACKNOWLEDGEMENT

I would like to express my sincere gratitude to my physics

mentor Mrs Sindhu for her vital support, guidance and

encouragement without which this project would not have

come forth from my side.

I would also like to express my hearty gratitude to the lab

assistant Mrs. Dipa for her support during the making of this

project.

I am indebted to my principal, Mrs. Shantha Maria James and

CBSE for providing me with this opportunity.

Special Thanks to my parents who helped me during the

development of this project with their advice. Without the

support extended by my friends , this project would not have

attained its present form and moreover I would like to thank

the Almighty God , for his abundant grace.

Abel Thomas

XII-A

INTRODUCTION

Security is the most important factor in today’s life. A lot of thefts happen everywhere, even the technology the crime gang use improves the way they perform their crime.

The technology of security should also be the best to prevent a crime. So I have prepared a security project. In this project a laser light is used to cover a specific area.

Laser lights go a long distance without experiencing scattering effect and also the light is only visible at source and incident point.

These properties helps to build a modern security system which may be named as “Laser Security System”.

When any person or object crosses the line the security alarm will start ringing.

Mirrors are kept to reflect the laser beam to cover more area.

COMPONENTS

1. LDR (Light Dependent Resistance):

LDR or photo resistor is a light controlled variable resistor. The resistance of a photo resistor decreases with increasing incident light intensity, in other words, it exhibits photoconductivity.

2. RESISTOR

A resistor is an electrical component that limits or regulates the flow of electrical current in an electronic circuit. Resistors can also be used to provide a specific voltage for an active device such as a transistor.

3. BUZZER

A buzzer is an electrical device that makes a buzzing noise and is used for signaling.

4. LASER POINTER

A laser pointer is a small device with power source (usually a battery) and a laser module emitting a very narrow beam of visible light, intended to be used to highlight something of interest by illuminating it with a small bright spot of coloured light.

7. BATTERY HOLDER

A small box like structure in which springs and small plates are attached so that the cells can be connected together easily.

CIRCUIT DIAGRAM

2.2KΩ Resistor (^) BUZZER

JLDR

KEY

LED

BC TRANSISTOR

LASER

WORKING

1. This circuit is based on LDR, a variable resistor in which the resistance varies according to the light intensity that falls on it.

2. The LDR and resistor form a potential divider network, which is the main part of our security alarm circuit.

What is transistor switch? One of the most common uses for transistors in an electronic circuit is as simple switches. In short, a transistor conducts current across the collector-emitter path only when a voltage is applied to the base. When no base voltage is present, the switch is off. When base voltage is present, the switch is on.

3. The voltage drop across the LDR is used to drive the transistor switch. When the voltage drop is above cut in voltage the transistor is turned on.

4. LDR has low resistance (m Ω range) in the presence of light and high resistance (M Ω) in the absence of light.

5. In our security alarm, a laser light is allowed to fall on the LDR continuously.

6. Light from other sources should not be allowed to fall on the LDR, so place the LDR in a box with a single hole to pass laser.

7. In this situation, the resistance offered by LDR is too low, since the Laser light is continuously allowed to fall on the LDR surface.

8. Thus the voltage drop across the LDR is also low (V=IR, Ohm’s law) which is insufficient to turn ON the transistor, so the transistor remains in switched OFF state.

9. When an intruder makes a disturbance to the continuous flow of laser beam, then the light falling on the LDR gets blocked. Thus its resistance increases to a higher value in the order of M Ω range (According to Ohm’s law).

10. While the resistance increases, the voltage drop also increases. When this voltage drop exceeds the cut in voltage of the silicon NPN transistor (BC547), it will turn ON.

11. Then current from starts flowing to ground via buzzer and transistor, which triggers the buzzer.

12. The beeping sound of the buzzer gives the indication of a security breach.

ADVANTAGES OF LASER

SECURITY

1. The circuit, construction and setup for the Laser Security System are very simple.

2. Is used with a battery, the laser security system can work even when there is a power outage.

3. Laser Security System can be used in safety lockers in our homes. Where even if the locker’s code is hacked, if acts as an additional layer of security.

4. In order to secure a larger area, reflectors can be used where each laser point contacts any surface.

5. Apart from security systems, this laser-based setup can also be used to check if pets or babies crossed a certain boundary.

BIBLIOGRAPHY

 www.answers.com

 www.google.com

 www.wikipedia.com

 www.slideshare.net

 www.academia.edu